Grey Screen on bootup

[medievil2003]

Hi all,

Hope you can help. I've got an iMac (27" Mid 2011) running Sierra. A week ago, i turned it on and was welcomed by the apple logo then half way through i got a grey screen which darkened slightly and just stayed like that. I tried everything to the best of my knowledge..

• PRAM Reset,
• SMC Reset
• Single user mode to check the disk with fsck -fy
• Diagnostic shows nothing in basic and extended tests
• Reinstalled Sierra

I originally thought it could be the graphics card but a few days after it would just start. I've been using it now for the past 5 days until i go to turn it on this morning and back to the grey screen.

The apple logo appears but then it flashes for a second to the grey screen.

Any ideas what this could be? I cant get into the recovery partition nor internet recovery. I've also tried to put another HDD in with sierra installed but same problem.

Thank you.

 

[Audit13]

Sounds like a video card issue. My late 2011 15.4" exhibited the same behaviour until I had the gpu chip replaced.

https://9to5mac.com/2013/08/16/appl...-replacement-program-for-some-mid-2011-imacs/

 

[medievil2003]

Hi Audit13, thanks for your reply.

That's what I've been reading but I've literately been on YouTube all day, played some online games etc and it's not gone off. Can it happen as random as a week or two then bad again?

Thanks

 

[Audit13]

Yes, that can happen. Some apps, like mail and safari, don't use hardware acceleration and would not cause a failure.

Once the amd gpu is utilised, it starts to warm up and it's contacts will lift off the logic board. Eventually, the contacts will stay separated.

For me, it happened slowly and wasn't a problem as long as I don't use apps that utilised the amd gpu.

 

[medievil2003]

I see, thank you. Do you know what apps will use hardware acceleration so i can test it?

 

[Audit13]

You can try cinebench 15: https://www.techspot.com/downloads/6709-cinebench.html